Fifty-six percent of likely voters said they would back an unnamed Republican candidate for Congress in a test of a low-turnout scenario for the crucial midterm elections. Thirty-nine percent in that same model said they would back a Democratic candidate, an increase by one percent over last week.

In Gallup's high-turnout model, Republicans maintain a 53-41 percent advantage among likely voters. That also represented a one percent tick upward in support for Democrats.

The poll suggests that the GOP hasn't lost any steam in its bid to pick up 39-plus seats they need in the House to reclaim the majority. Democrats have claimed that support for Republican candidates has peaked, and that they're primed to make inroads into support for the GOP, though Gallup's weekly effort to track the generic ballot suggests that any Democratic gains have been marginal at best.

The data also comes after a week in which Democrats, led by President Obama, have pivoted to train their sights on groups that have spent on behalf of the GOP in the elections. The administration thinks it can get political traction from its attacks on the U.S. Chamber of Commerce and American Crossroads by claiming those groups are spending foreign money on elections without having to disclose their sources of funding.

The latest poll, conducted Sept. 30 to Oct. 10, has a three percent margin of error for its sample of likely voters.